Grumpy John
3rd February 2010, 05:26 PM
After turning a crankshaft at groggys last Sunday I thought that it might be fun to have a crack at something more realistic. I searched the internet for a drawing of a crankshaft and came up with this.
128692
Using a vernier I roughly dimensioned the drawing.
I located what I thought would be a suitable piece of timber and cut it to length, mounted it between centres and did a test cut at each end to make sure it would turn to size.
128693
I then roughed out to the largest diameter and marked the position of the 2 large diameters and using a useless* 6mm parting tool I turned them to size.
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I then turned a 40mm spigot for the Escoulen cup chuck.
128696
I then mounted the blank in the Escoulen chuck and marked the position of #2 main bearing and turned it to size.
128698 128699
I marked where the 4 pin bearing diameters were located and removed some excess weight to help minimise vibration. I also marked the corresponding points on the chuck body.
128704 128705 128706 128707 128708 128709
Time to have some fun. I offset the chuck 25.5 mm and adjusted the counterweights as best I could. There was still some vibration (note to self, make some extra weights to bolt on to the counterweights), but I could get the lathe up to ~350 RPM without shaking everything to pieces. If you look closely at the chuck you can see the offset. I then turned pin dia. #2.
128710 128711 128712
Pin #4 went without a hitch, but it was obvious by now that I had not chosen a very suitable piece of timber for this project as there were a few splits developing. After barely touching the tool (the useless* 6 mm parting tool) to the timber the whole thing fell apart :doh:.
128714 128715
Things I have learnt from this project:
1. Cypress Pine is NOT suitable material for making a crankshaft.
2. don't do the offset in one hit, sneak up on it in 5mm increments.
3. The Escoulen chuck is good fun if you're not scared of turning air.
I would love to have another shot at turning a crankshaft, but this time with a more suitable blank. Can anyone recommend a suitable timber for this project. I'm thinking one of the dense desert timbers i.e Gidgee etc., but you don't usually get them as big as 95mm dia.
*Sorry Jeff, I couldn't help myelf :p.
128692
Using a vernier I roughly dimensioned the drawing.
I located what I thought would be a suitable piece of timber and cut it to length, mounted it between centres and did a test cut at each end to make sure it would turn to size.
128693
I then roughed out to the largest diameter and marked the position of the 2 large diameters and using a useless* 6mm parting tool I turned them to size.
128694 128695
I then turned a 40mm spigot for the Escoulen cup chuck.
128696
I then mounted the blank in the Escoulen chuck and marked the position of #2 main bearing and turned it to size.
128698 128699
I marked where the 4 pin bearing diameters were located and removed some excess weight to help minimise vibration. I also marked the corresponding points on the chuck body.
128704 128705 128706 128707 128708 128709
Time to have some fun. I offset the chuck 25.5 mm and adjusted the counterweights as best I could. There was still some vibration (note to self, make some extra weights to bolt on to the counterweights), but I could get the lathe up to ~350 RPM without shaking everything to pieces. If you look closely at the chuck you can see the offset. I then turned pin dia. #2.
128710 128711 128712
Pin #4 went without a hitch, but it was obvious by now that I had not chosen a very suitable piece of timber for this project as there were a few splits developing. After barely touching the tool (the useless* 6 mm parting tool) to the timber the whole thing fell apart :doh:.
128714 128715
Things I have learnt from this project:
1. Cypress Pine is NOT suitable material for making a crankshaft.
2. don't do the offset in one hit, sneak up on it in 5mm increments.
3. The Escoulen chuck is good fun if you're not scared of turning air.
I would love to have another shot at turning a crankshaft, but this time with a more suitable blank. Can anyone recommend a suitable timber for this project. I'm thinking one of the dense desert timbers i.e Gidgee etc., but you don't usually get them as big as 95mm dia.
*Sorry Jeff, I couldn't help myelf :p.